Apparatus for washing paper stock



June 8, 1948. s.v D. WELLS 2,442,990

APPARATUS FOR WASHING PAPER STOCKA Filed June 24, 1942 Patented June 8, 1948 APPARATUS FOR WASHING PAPER STOCK Sidney D. Wells, Combined Locks, Wis., assignor to The Institute of Paper Chemistry, a corporation of Wisconsin Application June 24, 1942, Serial No. 448,258

lClaim. l

The invention relates to improvements in process and apparatus for washing paper stock. Although capable of other uses, it is of particular value in washing paper stock made from. waste paper which originally carried a large amountI of ink or similar impurities.

Although various methods, some more or less successful, 4have been employed for freeing or getting rid of ink from waste paper which is to be used in the making up of a paper furnish, the linal washing of the de-inked paper stock has been attended with considerable difllculty. One of the difficulties has been the removal of the slime or scum which, usually in the form of bubbles or foam, accumulates in the vat or other receptacle which contains the stock during,'or subsequent to, the actual washing operation. The concentration of ink pigment in this scum. especially as the washing approaches completion, is many times greater than in the stock, and it is consequently a serious source of contamination of the otherwise well-washed stock.

The principle object of the present invention is to provide a method and apparatus for washing the so-called de-inked paper stock in such manner that-any residual ink or other waste material will not be carried along with the stock into the paper furnish in the form of bubbles which might interfere with the web-forming operation at a later time and more especially soil or contaminate the otherwise well washed stock.

In illustrating a preferred embodiment of my invention, I have selected a three-stage Washer which is set forth in the drawings wherein:

Fig. 1 is a somewhat diagrammatic view of the three-stage washing apparatus;

Fig. 2 is an enlarged vertical section through one of the washing vats; and

Fig. 3 is a plan view taken on the line 3-3 of Fig. 1.

The fiow of paper stock from which the ink has been -freed is conducted through the usual apparatus for the purpose of removing heavy particles and over a screen arrangement Ill to remove coarse ber bundles and other unwanted objects. From the screen I0, the stock is conducted through a pipe I I into the axially vertical cylinder tank I2. I'he inflow pipe II discharges into the upper end of said cylindrical tank I2, and has its lower end arranged at a tangent as shown at I3 in Fig. 3, so that the liquid in the tank will be given an anti-clockwise swirling movement around a vertical axis coinciding with the axis of the tank I2.

- Above the tank I2 is located the vat I4 in which Cil 2 rotates on a horizontal axis the cylinder Vmold I5 of the usual construction. Said cylinder mold I5 rotates in the direction of the arrow I6, and the stock is admitted to the descending side of the cylinder I5 over a Weir or battlev Il which divides the main part of the vat I 4 from a distributing box I8. The lower end of said distributing box or head box I8 is connected to the upper end of a conduit I9 through which stock is conveyed upwardly by the pump 20 drawing from the lower end of the tank I2.

As shown best in Fig. 2, the web formed on the screen 2| of the cylinder mold is removed by a couch roll 22 which revolves in the direction of the arrow 23 and from which the stock is stripped by a doctor knife 24. The lower part of lthe doctor knife 24 extends at rather a sharp angle to the upper end of the partition 25 which constitutes the outer wall of the overflow compartment 26 which receives any stock or pulp which flows over the upper end of the baffle 2l. It will be observed that the baille 2l is slightly lower than the inflow baille I1, so that it is possible to have a substantial overiiow 28, while at the same time there is a satisfactory distribution of stock due to y thestock owing over the inflow bale Il.

The pulp from the overflow compartment 26 flows therefrom into a conduit 29 which conducts the pulp into an upper zone of the tank I2 through a substantially horizontal conduit 3D which is arranged in substantially a tangential position in reference to the cylindrical tank I2,

dition, the pump 20 and conduit I9 will deliver into' the head boxI8 a considerably greater volume of pulp than is represented by the outflow of waste water which is drained through the screen 2l of the cylinder and flows 01T through the usual discharge pipes 3l which lead to the sewer. Hence, there will be a substantial amount of pulp overflowing the baille 21 into the overiiow compartment 26. This overflow is of sucient volume to carry off any slime or bubbles which are carried around with the cylinder mold as it revolves in the vat, and these bubbles, etc., in the overow are discharged into the cylinder I2. Because of the swirling action due to the tangential inow pipes I3 and 30. the latter partcles, i. e., the foam, accumulate in the center of the upper zone of the tank I 2, as indicated at 32, and from time to time, as they accumulate, they may be drawn off through a suction pipe 33 which is connected to a horizontal discharge pipe 34 leading into a suction fan or pump 35.

In many cases, it is advisable to re-wash the pulp after it has been subjected to the first washing treatment just described. To this end, the washed pulp which is removed by doctor 24 is conducted into a second washing apparatus 36 very similar to the one previously described, and, if necessary, to still another cylinder apparatus 31 by which time it is in proper condition to be used in making the paper.

Describing the arrangements of the third or iinal washing apparatus 31, it will be seen that everything about it is the same as in the case of the vat I4 and associated arrangements, it being understood, however, that the pulp which is removed from the couch roll 38 by doctor 39 is then ready to be used in making up the furnish for the paper machine. The tank 40 associated with the vat 31 receives its supply of pulp from the second stage of the washing through the tangent pipe 4l. Said pulp which enters tank 40 through conduit 4| is made of the proper consistency by means of a pure water spray 42 located above the inclined doctor 4,3 which removes the stock from the couch roll 44 of the second cylinder mold. Also, the eiiiuent from the cylinder mold in vat 31, which is discharged through the waste water pipes 4E, is discharged not into the sewer, but into the washed stock compartment 46 of the rst vat, so that the water is in effect re-used for re-washing the pulp after it has been first washed in the vat I4. A suicient volume of water ows through the exit pipes 45 from the vat 31 in order to form a liquid pulp of proper consistency to be washed effectively in the second stage of the apparatus. The diluted stock in compartment 46 flows through conduit 50 into the second washing unit.

As to the end discharges 41 of the second cylin-l der mold, these also are not connected to the sewer but to the inlet of a pump 43 which, by means of a pipe 49, conveys the eiiluent into the box of the screen I where said, effluent is mixed with the incoming flow stock. Hence, it will be seen that the only eiuent which is connected directly to the sewer and hence wasted is the eiluent from the first washing stage, out of pipes 3 The scope of the invention is to be determined by reference to the appended claim.

I claim:

A paper stock washing machine comprising a battery of connected tank and vat units means connected with each of said tanks for effecting the foam-removal of foreign ingredients. means 4 for introducing raw stock into the tank of the first tank-and-vat unit, a pair of vertically-disposed horizontally-spaced weirs in each of said vats for separating the interior thereof into a stock inlet distributing compartment, a stock overilow outlet compartment, and an intermediate mold compartment, a rotatable mold in each of said vats equipped with means for collecting and removing stock fibers therefrom for delivery outside of the respective connected tankand-vat unit, conduit means for conveying the stock from each of said tanks to the inlet distributing compartment of the vat of the respective unit, other conduit means connecting the stock overflow outlet compartment of each vat with the tank of the corresponding unit so as to resubject the stock overflow to the foam-forming agitation ot said tank, third conduit means for delivering the iibers from one mold tangentially into the upper zone of the tank of the subsequent tank-and-vat unit whereby said bers are resubject to swirling agitation, and means for removing the water from the interior of each of said molds.

SIDNEY D. WELLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENT Number Name Date 718,651 McConvllle Jan. 20, 1903 813,984 MacNaughton Feb. 27, 1906 983,441 Harvey Feb. 7, 1911 1,245,839 Waring Nov. 6, 1917 1,396,227 Marr Nov. 8, 1921 1,405,944 Shartle Feb. 7, 1922 1,468,337 Winestock Sept. 18, 1923 1,632,802 Richter June 21, 1927 1,700,925 Dezurk Feb. 5, 1929 1,707,604 Fisher Apr. 2, 1929 1,746,434 Lowe Feb. 11, 1930 1,828,279 Brown Oct. 20, 1931 2,005,839 Edge June 25, 1935 2,018,938 Wells Oct. 29, 1935 2,060,685 Murphy Nov. 10, 1936 2,077,059 Snyder Apr. 13, 1937 2,078,810 Richter Apr. 27, 1937 2,098,608 Berges Nov. 9, 1937 2,116,511 Earle May 10, 1938 2,193,032 Mackenzie Mar. 12, 1940 2,249,128 Goldsmith July 15, 1941 2,331,455 Cowles Oct. 12, 1943 2,355,243 scheid Aug. 8, 1944 OTHER REFERENCES Technical Association Papers Series 19 (1936), pages 167 to 171. 

